The invention is a process for the production of 2,4,6-trimethyl pyridine wherein a carbonyl compound is reacted with ammonia to form a mixture containing 2,2,4,6-tetramethyl-1,2-dihydropyridine, the mixture is purified and the purified mixture is converted to 2,4,6-trimethyl pyridine in high yields.
Technical grade collidine or 2,4,6-trimethyl pyridine (TMP) is commercially available as a coal tar extract and contains a mixture of trimethyl and dimethyl pyridines which are difficult to separate due to their close boiling points.
There are many known synthetic methods to make 2,4,6-trimethyl pyridine as is illustrated by U.S. Pat. Nos. 3,781,292; 3,829,429 and 4,140,690.
It is known from U.S. Pat. No. 2,796,421 to react ketones and ammonia over a catalyst to make trimethyl pyridines. However, these single pass processes give low yields as is shown by the controls set forth herein.